JPH02205982A - Picture processor - Google Patents

Abstract

PURPOSE:To always obtain an optimum compression/expansion ratio by switching the data compression algorithm of a data compressing means according to the identification result of an identification means. CONSTITUTION:A switching means 21 is provided to switch the data compression algorithms of data compressing means 22-24 according to the identification result of the identification means 1. Namely, the data compressing means 22-24 are equipped with the plural data compression algorithms and the identification means 1 identifies the character of original picture data based on statistical distribution concerning the color information of the original picture data. Then, the switching means 1 switches the data compression algorithms of the data compressing means 22-24 according to the identification result of the identification means 1. Accordingly, optimum data compression processing can be always executed automatically in correspondence to the kind of the original picture data.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image processing apparatus, and particularly to an image processing apparatus that compresses color image data.

In addition, the image processing device of the present invention can perform a wide range of color image data searches, communications, and
Available for editing and printing equipment.

[Prior Art] Today, color images handled by this type of image processing apparatus include, for example, natural images such as photographs, illustrations (sketch) images drawn by illustrators, and character images mainly consisting of characters. Conventionally, these image data were processed using a single compression/decompression algorithm.

FIG. 9 is a block diagram of a conventional image data retrieval system. In the figure, reference numeral 100 denotes an input means for inputting image data of various images.

101 is a man-machine interface (MMI) consisting of a keyboard and pointing device for an operator to interact with the system. A calculation means (CPU) 102 performs calculations for registering or searching various image data, and also controls its peripheral devices. 103 is an output means (CRT), which displays a registered image or a search image according to a command. Reference numeral 104 denotes a recording means, which stores various types of image data in a compressed form, an index file for searching the image data, and the like. The recording means 104 consists of an optical disk device or a magnetic disk device. A memory 105 has a storage area for image data and a work area used by the CPU 102. A compression/expansion means 106 compresses or expands image data according to a single compression/expansion algorithm.

With this configuration, when registering an image, the image data input by the input means 100 is temporarily stored in the memory 105, and a keyword for specifying the image is input by interactive operation via the MMIIOI. As a result, the input keyword is registered in the index file of the recording means 104, and the image data is compressed according to the data compression algorithm of the compression/expansion means 106, so that the image data corresponds to the keyword in the index file of the recording means 104. recorded by name.

Further, when searching for an image, a keyword for calling up the image is inputted through an interactive operation via the MMIIOI. The calculation means 102 reads the corresponding image data from the recording means 104 according to the input keyword, the compression/expansion means 106 expands this image data according to an algorithm opposite to compression, and the output means 103 reads out the expanded image data ( For example, color R, G, B data) are displayed.

[Problems to be Solved by the Invention] However, when image data is processed using a single compression/expansion algorithm as described above, a sufficient compression/expansion rate may not be obtained depending on the type (characteristics) of the image. Furthermore, if one type of image is prioritized, other types of images will be sacrificed. Furthermore, if an attempt is made to satisfy all types of images, the overall compression/expansion rate will not increase.

The present invention eliminates the above-mentioned drawbacks of the prior art, and its purpose is to provide an image processing device that can always obtain the optimum compression/expansion ratio depending on the type of image.

[Means for Solving the Problems] In order to achieve the above object, the image processing device of the present invention has the following features:
data compression means comprising a plurality of data compression algorithms; identification means for identifying the nature of the original image data based on statistical distribution regarding color information of the original image data; The outline thereof is to include a switching means for switching compression algorithms.

[Operation] In this configuration, the data compression means includes a plurality of data compression algorithms. The identification means identifies the nature of the original image data based on the statistical distribution of the color information of the original image data. The switching means switches the data compression algorithm of the data compression means according to the identification result of the identification means.

As a result, optimal data compression processing is automatically and always performed depending on the type of original image data.

[Description of Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of an image search device according to an embodiment. In the figure, 1 is a control processor unit (
CPU), which controls the entire image search device. A program memory 2 stores, for example, control programs shown in FIGS. 5 and 9 to be executed by the CPU 1. 3
is a parameter controller which, under the control of the CPU 1, controls the initialization, setting, comparison calculation, etc. of various parameters necessary for the processing described below. 4 is a parameter memory that stores various parameters. Reference numeral 5 denotes an arithmetic unit, which performs comparison calculations of various parameters, etc. Reference numeral 6 denotes a parameter setting I10, which provides an interface for parameter setting performed by an operator. Reference numerals 29 and 30 denote a keyboard and a digitizer, respectively, through which commands and parameters such as image registration or search requests are inputted via the parameter setting l106.

Reference numeral 20 denotes a CRT, which displays, for example, menu contents when setting parameters. Operator is CRT2
The parameter considered to be optimal among the display parameters of 0 is selected using the keyboard 29 or the digitizer 30. 1
A CRT controller 9 controls the display of the CRT 20.

Reference numeral 7 denotes an index file, which records the identification code, attribute data, etc. of the image used for image registration and search. Input of attribute data is performed by a selection operation on the CRT 20 using the keyboard 29 or digitizer 30. This index file 7 is provided, for example, on a magnetic hard disk. 8 is an image file, and the image data is recorded in correspondence with the identification code and attribute data registered in the index file 7. The image file 8 is provided, for example, on a magneto-optical recording medium.

22 is an image compressor A, for example, a sketch image.
It is configured to use vector quantization to maximize the data compression rate for image data with a small number of colors. Reference numeral 26 denotes an image decompressor A, which is in a paired relationship with the image compressor A, and restores the original image data using an algorithm opposite to that of the image compressor A. Reference numeral 23 denotes an image compressor B, which is configured to handle natural images such as photographs, for example.

In this embodiment, the original image data of R, G, B coordinate system, Y, I
, Q system image data, and compresses the R, G, and B 8 bits each into image data of Y=8 bits, I=5 bits, and Q=5 bits. 27 is an image decompressor B, which is in a paired relationship with the image compressor B;
The original image data is restored using the reverse algorithm.

Note that the image compressor/decompressor B may be configured according to the vector quantization method. Reference numeral 24 denotes an image compressor C, which is configured to maximize the data compression rate using the run-length method for images such as characters and graphics. Reference numeral 28 denotes an image decompressor C, which is in a paired relationship with the image compressor C, and restores the original image data using an algorithm opposite to that of the image compressor C. 21 is an image compressor switching means, and the CPU 1
selects one of the image compressors A-C under the control of the image compressor A-C. Reference numeral 25 denotes an image expander switching means, which selects one of the image expanders A to C.

In this way, CPU 1 decompresses with decompressor A when compressed by compressor A, decompresses with decompressor B when compressed with compressor B, and decompresses with decompressor C when compressed with compressor C. Control switching.

34 is an image processing unit that performs processing other than compression and expansion of image data. In the image processing unit 34, an image processor 10 performs core processing of the image processing unit 34. The image processor 10 includes image controllers 9 and C.
It is connected to CPU1 via PU bus 33, and the CPU
According to the command from U1, the image memory 12.1 described below
3 or via an image data l1016 to be described later, and performs various arithmetic processing.

The image processor 1o performs four arithmetic operations, logical operations, maximum value/minimum value operations, etc. between each brane 12a, 12b, 12c of the image memory 12.13 or between these and arbitrary constants, and for example, performs R for each pixel. , G, B data and find the difference between them.
, B data in other dimensions (e.g. H, L, S, Y, etc.).

Q coordinate system, etc.). The calculation result is stored in the image memory 12 or 13. Image memories 12 and 13 each have three channels (for example, R, G,
B or H, L, S, etc.) frame (brane) configuration a,
b and c, and is connected to both the CPU bus 33 and the video bus 35. Therefore, the CPUI can read and write any of the image memories 12 and 13, and the image processor 10 can perform image data calculations between arbitrary image memories.

11 is a flag map memory, and image memory 12
．． This memory stores flags and the like generated as a result of various calculations on the image data of 13 at addresses corresponding to the image memories 12 and 13. Flag map memory 11
are each brane 12a, 12 of image memory 12.13
b and 12c, and the presence of the flag map memory 11 allows for high-speed statistical calculations (histogram calculations, etc.) on image data.

14.15 is a look-up table made of high-speed RAM, the input of which is connected to the video bus 35 side of the image memory 12.13.

Each of the frame memories a, b, and c of the look-up tables 14 and 15 has an address space of (8 bits x 256). Also, lookup tables 14 and 15 for each frame memory a and b.

The address input to C is performed by the corresponding image memory 12.
．． 8 bits from each of the 13 branes a, b, c (256
gradation) output, and lookup table 14.1
The output data lines of each of the frame memories a, b, and c of 5 are connected to a video bus 35. The CPUI can freely read and write the contents of the lookup tables 14, 15 via the image controller 9 and image processor 10.

17 is a graphics controller, and video bus 3
Display control of video data on 5.

A graphic CRT 18 displays video data output from the graphic controller 17. Reference numeral 16 denotes an image data I10, which interfaces image data input from a three-tube camera 31 or a color CCD scanner 32, which are image input devices.

With this configuration, when registering image data, the original image data read into the image memory 12 or 13 is statistically analyzed and a compressor according to the characteristics of the image is automatically selected. The code of the selected compressor is included and registered in the attribute data of the index file 7, and the compressed image data is written to the image file 8.

Further, when searching for registered image data, the code of the compressor is read out from the attribute data of the index file 7 and the corresponding decompressor is automatically selected.

As a result, the image data of the image file 8 is restored by the selected decompressor and displayed on the screen.

FIG. 2 is a diagram showing the image data storage structure of the image memory 12 of the embodiment. In FIG. 0, R(i, j),
G (i, j) and B (i, j) represent R, G, 8 image data at address (i, j), respectively. R,G,
8 image data consists of 8 bits each, 25 from 0 to 255.
Can express 6 gradations. Also, address (i, j) is (1,
1) to (512,512), and the size of one image is (512×512) pixels. The same applies to the image memory 13.

FIG. 3(A) is a diagram showing the data storage structure of the index file 7 of the embodiment. When registering image data,
Original image data input from the three-tube camera 31 or COD scanner 32 is stored in the image memory 12 or 13 and displayed on the graphic CRT 18. The operator looks at this displayed image, uses the keyboard 29 to input a title and comment about the image, and uses the digitizer 30 to input attribute data about the image. The CPU 1 generates an identification code 71 for the image from these input data.

The CPU 1 also instructs the image processing unit 34 to perform statistical processing on the image data, and includes the properties of the resulting image (compressor code) in the attribute data. The identification code 71 and attribute data 72 thus obtained form a pair and constitute one record 70, which is registered in the index file 7 as an index of the image.

FIG. 3(B) is a diagram showing the data storage structure of the image file 8 of the embodiment. In the figure, 71 is an identification code corresponding to the index file 7, and 80 is image data obtained by compressing original image data by a selected image compressor. The identification code 71 and the image data 8o form a pair to form a data file 82 that indexes the image data.

FIG. 4 is a diagram showing the storage format of the record 70 of the embodiment. In the figure, the record 70 consists of 94 bytes in total, of which the identification code 71 = 4 bytes, the title record = 24 bytes, and the comment code = 5.
It is 0 bytes. Further, each of the compression code, input device code, person code, scenery code, animal code, plant code, emotional expression code, and color expression code is 2 bytes.

The character code input by the operator using the keyboard 29 is written in the title code and comment code columns. The compression code column contains CPU 1 and image processing unit 3.
The attribute data (
code corresponding to the I10 address of the selected compressor, etc.)
In this embodiment, the lower 3 bits are used as the compressed code, and the rest are left unused. The first lowest bit of the three lowest bits represents a pair of image compressor A and image decompressor A, the second lowest bit represents a pair of image compressor B and image decompressor B, and the third lowest bit represents a pair of image compressor B and image decompressor B. The bit is image compressor C
and image decompressor C, that is, the lower three bits are "001" when the selection is A, "010" when the selection is B, and "100" when the selection is C. In this embodiment, when the image compressor is selected, the attribute is a sketch image, when the image compressor is selected, the attribute is a photographic image, and when the image compressor is selected, the attribute is a character image. In this way, the information in the compression code column is used for the purpose of switching the compressor or decompressor and determining the type of image.
This makes so-called keyword searches easy.

Furthermore, 2 bytes each are used for person code, landscape code, animal code, person code, emotional expression code, color expression code, etc.
16 bits) are allocated, and the presence or absence of each attribute is stored in bit units as shown in the figure. The most significant bit of each code is a presence flag indicating whether or not attribute information regarding people, scenery, etc. exists, thereby speeding up flag analysis.

The remaining 15 bits of each code are provided with 15 types of attribute flags. The concepts of various attributes correspond to the attribute flag bits as shown in the figure. For example, when the attribute related to "person" is "child" or "woman", the attribute code:=:
It becomes rlololoooooooooooooJ. Note that the latter 8 bits of the 2 bytes of the person code are left blank to accommodate future increases. Below, "Landscape"
~The same applies to "color expression".

FIG. 5 is a flowchart of the image registration processing procedure of the embodiment. The input image is a photograph of a woman, child, and dog together in a meadow, and the overall scene is bright.
Let the image be There are six attribute codes for this: ``person,''``landscape,''``animal,''``plant,'' ``emotional expression,'' and ``color expression.'' This case will be explained.

(Step Sl) Original image data is input via the image data l1016. To explain this manual image procedure in detail, first, use a CRT20
The type of image input device is displayed using an icon or the like, and the operator indicates a desired icon using the keyboard 29 or digitizer 30.

As a result, an input flag 40 (not shown) in the parameter memory 4 is set to "O" when the three-tube camera 31 is selected, and to "1" when the COD scanner 32 is selected, for example. give instructions,
The image processor 10 reads the original image data from the designated image input device via the image data l1016, and stores the original image data separately in R, G, and B data in the image memory 12a,
12b, 1"2c.

(Step S2) The operator inputs a title and a comment for the input image data. That is, first, a request for inputting the title and comment for the image is displayed on CR and T2O. The operator selects R, G, B from the image memory 12.
The user looks at the graphic CRT 1B displaying image data and inputs a title and comment using the keyboard 29. The title can be up to 24 characters, and the comment can be up to 50 characters.

(Step S3) Input attributes related to "person". That is, first, CRT2
0 is an attribute related to "person", such as "male""female""
Displays ``family'', ``children'', ``foreigners'', ``couples'', ``multiple people'', etc. The operator uses a graphic CRT1
While looking at the displayed image 8, the user extracts the relevant attribute, and selects and inputs it using the keyboard 29 or digitizer 30. You may select multiple attributes, or you may select none. In this embodiment, "woman" and "child" are selected.

(Step S4) In the same way, attributes related to "landscape" are input.

In this embodiment, "grassland" is selected.

(Step S5) Attributes related to "animal" are input. In this example, “dog”
Select.

("Step SS") Inputting attributes related to "plant" In this embodiment, "weed" (not shown) is selected.

(Step S7) Input attributes related to the "emotional expression" felt by the operator.In this embodiment, "generally bright scene" (not shown)
Select.

(Step S8) Attributes related to "color expression" are input. In this embodiment, "green", "blue", "yellow", "brown", etc. (not shown) are selected.

(Step S9) The above attribute input is confirmed. That is, all input attributes are displayed on the CRT 20 for the operator to confirm. If satisfied, it instructs to proceed to the next step (step 510), and if it is desired to make a change, it instructs to proceed to the opposite direction (step S2).

If the process proceeds to step s2, attributes can be input again.

(Step 510) The maximum value MAX(R(i,j),
Find G (i, j), B (i, J)). That is, the image processor 10 first compares the R data of the brane 12a and the G data of the brane 12b for each pixel, and stores the larger one in the brane 13a of the image memory 13. Next, the image data of the brane 13a and the B data of the brane 12c are compared pixel by pixel, and the larger one is stored in the image memory 1.
3 is stored in the brain 13b. The brain 13b of the resulting image memory 13 holds the maximum value for each pixel of RlG, 8 image data.

(Step 5ll) The minimum value MIN(R(i,j),
Find G (i, j), B (i, j)). That is, the image processor 10 first compares the R data of the brane 12a and the G data of the brane 12b for each pixel, and stores the smaller one in the brane 13a of the image memory 13. Next, the image data of the brane 13a and the B data of the brane 12c are compared pixel by pixel, and the smaller one is stored in the image memory 13.
is stored in the brain 13c. As a result, the brain 13c of the image memory 13 holds the minimum value for each pixel of RlG, 8 image data.

(Step S12) The difference between the maximum value and minimum value for each pixel determined for the R, G, and B original image data is determined. That is, the difference between the maximum value of the brane 13b and the minimum value of the brane 13c of the image memory 13 is obtained for each pixel, and this is written to the brane 13a of the image memory 13.

(Step 513) A histogram (distribution of the number of values of difference data 0 to 255) is obtained for the obtained difference data (brane 13a), and the result is stored in the parameter memory 4.
(Fig. 6). Specifically, the CPU 1 sequentially reads the difference data of the brain 13a, and when the difference data = "O", sets a flag "1" at the corresponding address of the flag map memory 11, and sets the flag 1" to the corresponding address of the flag map memory 11, and when the difference data = "0" is not set. Set the flag 0” at the time. Next, the number of differential data="0" for this one image is counted and the result is stored in the HINDo (0) area of the parameter memory 4. Next, a similar calculation is performed for the difference data="l", and the number of difference data="1" is stored in the HINDO(1) area. Similarly, HINDO(2) to HINDO(2
55).

Alternatively, the value of the difference data may be analyzed in steps of 10, for example. First, find the number of difference data = "0 to 9",
Next, find the number of difference data = "10 to 19°". In this way, the histogram will be HINDO (0) to
It fits in the HINDO (25) area.

(Step 514) Method for compressing original image data (compressor/expander A-
Select pair C). To do this, first, the characteristics of the image are determined based on the statistically calculated values in step S13 for the original image data.

FIGS. 7A to 7C are diagrams showing histograms of difference data obtained for each image in the example.

In the figure, the horizontal axis represents the difference data O to 255 in increments of 10, and the vertical axis represents the frequency of the sum of the numbers in each section.

FIG. 7(A) is a histogram of a sketch image. A sketch painting has fewer colors than a photographic painting, so the hues are brighter, resulting in a discrete histogram as shown in the figure. FIG. 7(B) is a histogram of a photographic image. Photographic images have a large number of colors, and the histogram has a Gaussian distribution as shown in the figure. FIG. 7(C) is a histogram of a character image. A character image consists of a background color and a character color and is highly monochromatic, so an extremely large histogram appears with a certain frequency as shown in the figure.

FIG. 8 is a flowchart showing details of step S14 in the embodiment. In the figure, the CPU first starts with HINDO.
Add (0) to HINDO (255) in increments of 10 to find the respective sums, then find the maximum of each added value and HI ND
Store in O-X.

In step S, 141, (HI NDO-X)>(HI
NDO-MOJ I').

Here, HINDO-MOJ I is a predetermined value that allows character images to be identified, and in this example, (512X512
) is 240,000, which is about 91.5% of the pixels. (H
When INDO-X)>(HINDO-MOJI), the process advances to step 5147 and a character image is selected. In step 5148, the compressor/expander C pair is selected.

Also (HINDO-X)> (HINDO-MOJI)
If not, proceed to step 5142, and (HENSA-X
)> (HENSA-5HASIN). Here, HENSA-X is the standard deviation of the frequency determined by CPUI from the above histogram. However, in this embodiment, the average value of the frequency is set to "0". Also HENSA-
SHASIN is a predetermined value (for example, 40) that allows a sketch image to be distinguished from a natural image.

(HENSA-X)> ()(ENSA-5RASIN
), the process proceeds to step 5145, where a natural image is selected.In step 5146, the compression/expansion unit B(7) pair is selected. Also (HENSA-X)>(HENSA-SH
AS IN), the process advances to step 5143 and a sketch image is selected.

In step 5144, the compressor/expander A pair is selected.

Such a judgment based on the maximum frequency value and standard deviation can be performed relatively easily, and the image identification accuracy is also extremely high. In this way, the type of image data is identified, the type of compressor/expander is selected, and this information is stored in DATA-ID.

(Step 515) CUPI generates an identification code 71, adds attribute data 72, generates a record 70, and registers it in the index file 7. In addition, DATA-ID is included in the attribute data.
It also includes information. In this way, the operator can work without being aware of actual data compression/decompression.

(Step 516) Under the command of the CPU1, the image processor 10 compresses the R, G, and B original image data in the image memory 12 using the selected compressor, and adds an identification code 71 to the beginning of the resulting image data. , and register it in image file 8.

Incidentally, in the above-described embodiment, processing related to setting attribute data, calculating statistical data of an image, etc. was performed by software, but it goes without saying that it can be implemented by hardware.

Further, in the above embodiment, one type of compressor/expander is selected for each image, but the present invention is not limited to this.

If image region separation technology is introduced, it is possible to select the optimal image compressor/decompressor for each of multiple regions of one image.

[Effects of the Invention] As described above, according to the present invention, highly efficient image processing can always be performed on various image data.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram of an image search device according to the embodiment. FIG. 2 is a diagram showing the image data storage structure of the image memory 12 according to the embodiment. FIG. 3 (A) is a data storage structure of the index file 7 according to the embodiment. Figure 3 (B) is a diagram showing the data storage structure of the image file 8 of the example. Figure 4 is a diagram showing the storage format of the record 70 of the example. Figure 5 is an image of the example. A flowchart of the registration processing procedure. FIG. 6 is a diagram showing a part of the storage structure of the parameter memory 4 of the embodiment. FIGS. 7 (A) to (C) are histograms of difference data obtained for each image of the embodiment. 8 is a flowchart showing details of step S14 of the embodiment, and FIG. 9 is a block diagram of a conventional image data retrieval system. In the figure, 1...CPU, 2...Program memory, 3
...Parameter controller, 4...Parameter memory, 5...Arithmetic unit, 6...Parameter setting machine/
○, 7... Index file, 8... Image file, 9... Image controller, 1o...
Image processing processor, 11...Flag map memory,
12゜13...Image memory, 14.15...Lookup table, 16...I10 for image data,
17...Graphic controller, 18...Graphic CRT, 19.CRT) controller, 2o...
・CRT, 21... Image expander switching means, 22 to 24
...Image compressor A-C125...Image expander switching means, 26-28...Image expander A-C129...Keyboard, 30...Digitizer, 31...Three-tube camera, 32... COD scanner, 33... CPU bus, 34... image processing section, 35... video bus. Patent applicant: Canon Co., Ltd. Figure 6 (Small) (Large) (Small) c Large) (Small) c Large) (A) (B) (C)

Claims (1)

[Scope of Claims] Data compression means comprising a plurality of data compression algorithms; identification means for identifying the nature of the original image data based on statistical distribution regarding color information of the original image data; and identification results of the identification means. Accordingly, an image processing apparatus characterized by comprising a switching means for switching a data compression algorithm of the data compression means.